More than 25% of children with Kawasaki disease (KD), the most common cause of pediatric acquired heart disease, develop coronary artery abnormalities (CAAs) despite standard therapy with intravenous immunoglobulin. Once aneurysms have formed, the damage to the arterial wall is irreversible, such as stenoses and calcification that may lead to ischemic complications. This collaborative team has established that activation of the IL-1 pathway and endothelial-to-mesenchymal transition (EndoMT) with downregulation of krppel-like factor 4 (KLF4) are key to the pathogenesis of KD vasculitis. Our novel discovery of the central role of TIFA (TNF receptor-associated factor-interacting protein with a forkhead-associated domain) in NLRP3 inflammasome activation in endothelial cell (EC) injury is proposed as a further mechanism of KD vasculitis. We propose a bold plan to unite this research team with expertise in vascular biology, immunology, and clinical KD to unravel the mechanisms underlying vascular injury in KD and pilot a novel therapeutic approach. The guiding hypothesis is that acute KD not only activates the IL-1/TIFA/NLRP3 inflammasome in the endothelium, but also reduces EC homeostasis, both of which are critical in the pathogenesis of KD. The blockade of the IL-1-dependent innate immune response by anakinra (recombinant IL-1R antagonist) in combination with the restoration of EC function by atorvastatin will reduce vascular damage in acute KD. Three specific aims are proposed to test this hypothesis. Specific Aim 1 will delineate the molecular basis by which anakinra blocks activation of the innate immune response associated with KD vasculitis. In vitro, ex vivo, and in vivo experiments will investigate the role of IL-1, TIFA, and NLRP3 in KD-mediated EC dysfunction and vasculitis using pathway-specific siRNA knockdown, recombinant overexpression, pharmacologic agonists and inhibitors (including anakinra), as well as loss-of- function mice. Specific Aim 2 will elucidate the molecular basis by which atorvastatin restores EC function in acute KD. Mouse lines with gain- and loss-of-function of KLF4 as well as lineage tracing experiments will be performed to decipher the molecular mechanisms underlying EC dysfunction in KD vasculopathy. Specific Aim 3 will determine the synergistic effect of anakinra/atorvastatin combination therapy in LCWE-injected mice and in KD patients. LCWE mouse models, including Tifa-/- and Klf4-/-, will be utilized to test the effect of anakinra/atorvastatin combination therapy on vascular inflammation and EC function. Furthermore, acute KD patients with early CAAs will be enrolled in a pilot study of anakinra/atorvastatin combination therapy. Cytokine levels and MMP activity in sera and transcript abundance in whole blood RNA will be measured pre- and post- treatment. These sera will also be tested in vitro with cultured ECs with read-outs for EC innate immune responses and EC dysfunction. The synergistic expertise of the three teams in this multi-PI proposal provides a unique opportunity to understand molecular mechanisms underlying KD vasculopathy and rapidly translate the findings into a pilot study in children with in vitro and in vivo assessments of the treatment effect.